Step 1

Place 8 tablespoons of the unsalted butter in a medium bowl and let sit at room temperature to soften while you make the dough.

Step 2

Place 4 1/4 cups all-purpose flour, 2 tablespoons granulated sugar, 1 packet active dry yeast, and 2 teaspoons kosher salt in the bowl of a stand mixer fitted with the hook attachment and whisk to combine. (Alternatively, place in a large bowl if kneading by hand.)

Step 3

Place 1 cup warm water (about 125ºF),1/4 cup toasted sesame oil, and 2 large eggs in a medium bowl and whisk to combine. Turn the mixer speed on to low and slowly pour in the egg mixture. Once all the egg mixture is incorporated, Increase the speed to medium-low and knead until the dough is smooth, soft, and forms a ball, 7 to 8 minutes. After 5 minutes, if the dough is sticking to the edges of the bowl, add more flour 1 tablespoon at a time. (If mixing by hand, stir until a shaggy dough forms, then knead on a work surface until a finger pressed into the dough springs back, about 7 minutes.)

Step 4

Gently remove the dough from the bowl and coat the bowl in cooking spray. Return the dough to the bowl. Tightly cover the bowl in plastic wrap and let the dough rise in a warm place until nearly doubled in size, about 1 1/2 hours. Meanwhile, make the filling when the butter in the bowl is softened.

Step 5

Prepare the following: Drain 2 cups cabbage kimchi in a fine-mesh strainer, pressing out any excess liquid with a rubber spatula. Place the kimchi in the bowl of a food processor and pulse until coarsely chopped, about 10 pulses. (Alternatively, chop the kimchi by hand.) Return the kimchi to the strainer and press out any excess liquid.

Step 6

Heat a medium non-stick skillet over medium heat. Add the kimchi and cook until some liquid has evaporated, 4 to 5 minutes. Transfer back to the strainer to drain and cool.

Step 7

Mince 4 garlic cloves and add to the bowl with butter. Thinly slice 3 medium scallions. Reserve 2 tablespoons of the greens for garnish, then add the remaining scallions to the bowl with butter. Add the cooled kimchi, 1 teaspoon kosher salt, and 1/4 teaspoon black pepper, and stir to combine.

Step 8

Grate 6 ounces sharp white cheddar cheese on the large holes of a box grater (about 1 1/2 cups). Coat a 9x13-inch baking dish with cooking spray.

Step 9

When the dough is ready, punch it down and transfer onto a lightly floured work surface. Flour a rolling pin and roll the dough into a 24x10-inch rectangle (about 1/3-inch thick), with a longer side closer to you.

Step 10

Evenly spread the kimchi filling onto the surface of the dough, then sprinkle with the cheese. Starting at the bottom, roll the dough up tightly into a log, using a bench scraper as needed to help release the dough from the work surface. Pinch the seam together at the top.

Step 11

Position the log seam-side down. Trim 1 inch off each end of the log and discard. Cut the log crosswise into 15 pieces. Arrange the rolls cut-side up in the baking dish, 5 across and 3 down.

Step 12

Loosely cover in plastic wrap and let rise at room temperature for 25 minutes. Meanwhile, arrange a rack in the middle of the oven and heat the oven to 350°F. Melt the remaining 2 tablespoons unsalted butter in the microwave or in a small saucepan.

Step 13

Uncover and brush the butter onto the rolls. Sprinkle with 2 tablespoons white sesame seeds. Bake until puffed, golden-brown, and a toothpick or skewer inserted in several spots comes out clean, 30 to 35 minutes.